A simple mathematical model can account for lizard’s green-and-black pattern

Enlarge / The patterns of the ocellated lizard are predictable by a mathematical model for phase transitions. (credit: UNIGE / Michel Milinkovitch)

Zebras and tigers have stripes, cheetahs and leopards have spots, and the ocellated lizard (Timon lepidus) boasts a labyrinthine pattern of black-and-green chains of scales. Now researchers from the University of Geneva in Switzerland have demonstrated with a simple mathematical equation the lizard's complex patterns, according to a recent paper published in the journal Physical Review Letters.

These labyrinthine patterns, which provide ocellated lizards with an optimal camouflage, have been selected in the course of evolution," said co-author Michel Milinkovitch, a theoretical physicist at the University of Geneva in Switzerland. "These patterns are generated by a complex system, that yet can be simplified as a single equation, where what matters is not the precise location of the green and black scales, but the general appearance of the final patterns."

As we've reported previously, a common popular (though hotly debated) hypothesis for the formation of these kinds of animal patterns was proposed by Alan Turing in 1952, which is why they are sometimes referred to as "Turing patterns." Turing's seminal paper focused on chemicals known as morphogens. His proposed mechanism involved the interaction between an activator chemical that expresses a unique characteristic (like a tiger's stripe) and an inhibitor chemical that periodically kicks in to shut down the activator's expression. The key is that the inhibitor diffuses at a faster rate than the activator, creating periodic patterning.

Read 10 remaining paragraphs | Comments